diff options
| author | Geert Uytterhoeven <geert@linux-m68k.org> | 2017-03-10 15:15:18 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-03-17 15:10:49 +0900 |
| commit | ac201479cc695cb0140e425b9ca8ab2ecdcd2f0d (patch) | |
| tree | 78929b3866d2bc0af026c538cd20b72de477c5da /drivers/auxdisplay | |
| parent | 39f8ea46724efbed3ca021863a22337c31be264c (diff) | |
| download | linux-ac201479cc695cb0140e425b9ca8ab2ecdcd2f0d.tar.bz2 | |
auxdisplay: charlcd: Add support for 4-bit interfaces
In 4-bit mode, 8-bit commands and data are written using two raw writes
to the data interface: high nibble first, low nibble last. This must be
handled by the low-level driver.
However, as we don't know in which mode (4-bit or 8-bit) nor 4-bit phase
the LCD was left, initialization must always be handled using raw
writes, and needs to configure the LCD for 8-bit mode first.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/auxdisplay')
| -rw-r--r-- | drivers/auxdisplay/charlcd.c | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c index 930ffb2fb317..b3a84e90a268 100644 --- a/drivers/auxdisplay/charlcd.c +++ b/drivers/auxdisplay/charlcd.c @@ -223,24 +223,46 @@ static void charlcd_clear_display(struct charlcd *lcd) static int charlcd_init_display(struct charlcd *lcd) { + void (*write_cmd_raw)(struct charlcd *lcd, int cmd); struct charlcd_priv *priv = to_priv(lcd); + u8 init; + + if (lcd->ifwidth != 4 && lcd->ifwidth != 8) + return -EINVAL; priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D | LCD_FLAG_C | LCD_FLAG_B; long_sleep(20); /* wait 20 ms after power-up for the paranoid */ - /* 8bits, 1 line, small fonts; let's do it 3 times */ - lcd->ops->write_cmd(lcd, LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS); + /* + * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure + * the LCD is in 8-bit mode afterwards + */ + init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS; + if (lcd->ifwidth == 4) { + init >>= 4; + write_cmd_raw = lcd->ops->write_cmd_raw4; + } else { + write_cmd_raw = lcd->ops->write_cmd; + } + write_cmd_raw(lcd, init); long_sleep(10); - lcd->ops->write_cmd(lcd, LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS); + write_cmd_raw(lcd, init); long_sleep(10); - lcd->ops->write_cmd(lcd, LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS); + write_cmd_raw(lcd, init); long_sleep(10); + if (lcd->ifwidth == 4) { + /* Switch to 4-bit mode, 1 line, small fonts */ + lcd->ops->write_cmd_raw4(lcd, LCD_CMD_FUNCTION_SET >> 4); + long_sleep(10); + } + /* set font height and lines number */ lcd->ops->write_cmd(lcd, - LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS | + LCD_CMD_FUNCTION_SET | + ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) | ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0)); long_sleep(10); @@ -482,7 +504,8 @@ static inline int handle_lcd_special_code(struct charlcd *lcd) /* check whether one of F,N flags was changed */ else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N)) lcd->ops->write_cmd(lcd, - LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS | + LCD_CMD_FUNCTION_SET | + ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) | ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) | ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0)); /* check whether L flag was changed */ @@ -716,6 +739,7 @@ struct charlcd *charlcd_alloc(unsigned int drvdata_size) priv->esc_seq.len = -1; lcd = &priv->lcd; + lcd->ifwidth = 8; lcd->bwidth = DEFAULT_LCD_BWIDTH; lcd->hwidth = DEFAULT_LCD_HWIDTH; lcd->drvdata = priv->drvdata; |